High-quality black-and-white photographs of large old machines and tools

[Jon]

Captioned as: "Steam tractor burning some oil."

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[Jon]

Robertson tube straightener. I believe this machine is from around the 1940s.

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[Toolmaker51]

As if I need another project; salvaged a decent amount of wiring from my building. It's been coiled but should be on spools. They were only 110v circuits and look good as new, so will reuse them as such. Goal of respooling is I have a measuring wheel, to avoid pulling what turns up too short.
I have plenty conveyor skate wheels, a length of good sized angle iron, just need to cobble up axles and adjusting screws.
Any suggestions?

[Frank S]

Robertson tube straightener. I believe this machine is from around the 1940s.

Fullsize image: https://s3-us-west-1.amazonaws.com/h...r_fullsize.jpg

My first thought when I saw the guy standing there was he looked like Liam Neeson standing there the resemblance is striking

[Big Sexy]

As if I need another project; salvaged a decent amount of wiring from my building. It's been coiled but should be on spools. They were only 110v circuits and look good as new, so will reuse them as such. Goal of respooling is I have a measuring wheel, to avoid pulling what turns up too short.
I have plenty conveyor skate wheels, a length of good sized angle iron, just need to cobble up axles and adjusting screws.
Any suggestions?

Well there a couple of different ways you can do it with less work. First and easiest way is to count the number of loops and multiple by the diameter of the coils. The second is more accurate but does require a decent quality multimeter. You take a resistance measurement of the coil and then determine what size of wire you have. Then look up the known resistance for the size of wire you have. Once you know the resistance per length of wire you then multiply or divide your resistance by the known resistance for length. I think that’s how the second is done. It’s been a while and would need numbers in front of me to refresh my memory lol. But it is still easily done.

[Toolmaker51]

I like the multi-meter solution. It will also start screening broken conductors.
1st priority remains building the straightener to respool the wire for storage an eventual use.

[Frank S]

I like the multi-meter solution. It will also start screening broken conductors.
1st priority remains building the straightener to respool the wire for storage an eventual use.

Also with the multimeter if you know the length & gage +the ohms the wire should be, if they are off by a large margin it means the wire has been overloaded not fit for installing in a circuit

[mklotz]

Well there a couple of different ways you can do it with less work. First and easiest way is to count the number of loops and multiple by the diameter of the coils. The second is more accurate but does require a decent quality multimeter. You take a resistance measurement of the coil and then determine what size of wire you have. Then look up the known resistance for the size of wire you have. Once you know the resistance per length of wire you then multiply or divide your resistance by the known resistance for length. I think that’s how the second is done. It’s been a while and would need numbers in front of me to refresh my memory lol. But it is still easily done.

Rather than looking up the resistance/length value for the wire, you'll get better accuracy by measuring resistance of a known length of the subject wire. You'll need a very accurate ohm meter; most are not terribly accurate for measuring small resistances. Very small resistances are normally measured with a current bridge arrangement...

https://en.wikipedia.org/wiki/Wheatstone_bridge

Let:

r = resistance of length l of wire
R = resistance of coil of wire
L = length of coil of wire

then:

r / l = R / L ; assume resistance per unit length is constant over length of wire

or:

L = R / (r / l) = (R / r) * l

Taking the derivative of 'L' wrt to 'r'...

dL = - (R / r^2) * l * dr = - (L / r) * dr

which will allow you to estimate the error in 'L', dL, for a given error in the measurement of 'r', dr.

[Big Sexy]

I knew there was a formula out there somewhere. Thx

[Toolmaker51]

What great site! I have a decent [?] meter but I suspect not in keeping with Marv's description.
Solution sounds like to check the coils as they are now; spool them being fed over my measuring machine to know length, and label the resistance results/ length. That should sort failed conductors immediately, and comparing the rest ought to be in a very narrow range. They were only a 110v lighting circuit, 15 60w lamps.
If not good, oh well. Have 13,000 feet of yellow/ brown/ orange for 440v, green/ white/ black for 110v, forgot what is on hand to do 240v, only 2 machines get that.
Again, great site, but its due to the participating members. I appreciate every morsel dispensed of heads up.